A light-curable resin composition can be used, in case it has the corresponding optical properties, in optical assembly applications such as liquid optically-clear adhesive for touch panel assemblies. Liquid optically-clear adhesive (LOCA) is a liquid-based bonding technology used in touch panels and display devices to bind the cover lens, plastic or other optical materials to the main sensor unit or to each other. Adhesives are used to improve the optical characteristics of the device as well as to improve other attributes such as durability.
For productivity during coating a low viscosity of the adhesive is desired, while higher viscosity is required for better lamination results.
WO 2012/036980 A2 discloses an adhesive composition which has a thixotropic behavior. Thixotropy is a shear thinning property. Certain gels and fluids that are thick (viscous) under static conditions will flow (become thin, less viscous) over time when shaken, agitated or otherwise stressed. It then takes a fixed time to return to a more viscous state. In accordance with the afore-mentioned document the thixotropic behavior of the adhesive composition is achieved by adding an inorganic additive like fumed silica. However, adding inorganic additives results in significant particle problems as fumed silica is a solid particle and affects the optical performance of the adhesive composition.